196,059 research outputs found
USP8, a regulator of endosomal sorting, is involved in mouse acrosome biogenesis through interaction with the spermatid ESCRT-0 complex and microtubules
No full textUbiquitin-specific peptidase 8 (USP8) is a deubiquitinating
enzyme that works as a regulator of endosomal sorting and
vesicle morphology in cultured cells. Its function in vivo is,
however, unknown as USP8 gene deletion leads to embryonic
lethality. Previously, we have shown that USP8 is highly
expressed in male germ cells. These cells develop a peculiar
acidic vesicle that is indispensable for fertilization, the acrosome;
USP8 might be involved in vivo in acrosomogenesis. The
objective of this study was to test this hypothesis by determining
if selective components of the early endosomal machinery
interact functionally with USP8 during acrosomogenesis using
protein-protein interaction assays and double/triple immunolabeling.
Moreover, by exploiting the characteristic of USP8 that
exhibits a microtubule interacting and trafficking/transport
(MIT) domain, we verified whether USP8 effectively associates
with spermatid microtubules by microtubule cosedimentation
and binding assays. USP8 was able to interact with spermatid
ESCRT-0 (endosomal-sorting complex required for transport-0)
and microtubule structures; USP8/ESCRT-0-labeled vesicles,
monitored by fluorescence microscopy, were found to contribute
to acrosome formation while USP8 can directly link, via its
MIT domain, the labeled vesicles/developing acrosome to
microtubules, which could favor both acrosome assembly and
shaping. VPS54, the vacuolar-sorting protein responsible for
early endocytic retrograde transport, was here detected for the
first time in male germ cells; VPS54 followed the intracellular
route of USP8/ESCRT-0-labeled vesicles during acrosomogenesis.
We concluded that in vivo USP8 has a role strongly
associated with acrosome biogenesis and that the early
endosome pathway is significantly involved in the process,
which suggests that the acrosome could be a novel lysosomerelated
organelle
mUBPY, endocytic vesicle traffic and microtubule mediated transport in acrosome biogenesis. Comparative study between wild-type and Wobbler (L967Q Vps54) mice
No full textAcrosome biogenesis is a multistep process, essential for fertilization, involving poorly understood events, like vesicular trafficking and microtubular transport. We found that the deubiquitinating enzyme UBPy, in mouse, marks step-by-step the development of the acrosomal vesicle. Recently by studies on transfected cells, UBPy is emerging to play a key and no redundant role in endosomal sorting, resulting to be fundamental for the cell life. In this work we studied in male germ cells the endosomal trafficking machinery, in particular we detected the early endosome compartment and the ESCRT-0 complex, interestingly mUBPy colocalizes and interacts with Hrs and Hbp (Hrs-binding protein) at the early endosomes. We investigated also Vps54, a component of the Golgi associated retrograde protein complex which is involved in vesicles transport from early endosomes to trans Golgi network. Altogether our findings demonstred for the first time the presence of a mutiprotein complex in spermatogenic cells. Interestingly, proteins belonging to vesicular compartment participate and cooperate with UBPy to the formation of the acrosome, and here remain in the mature sperm, strongly suggesting that the endosome system, through an UBPy-microtubular manchette-mediated transport, could contribute to the biogenesis of the acrosome. The missense mutation L967Q in Vps54 marks the wobbler mouse phenotype. Wobbler mouse is an animal model for motor neuron neurodegenerative disorders with associated male sterility. We provided the first characterization of wobbler reproductive apparatus, detecting the absence of the acrosome, an abnormal shape of sperm s head and a defective vesicular transport
cAMP-Epac2-mediated activation of Rap1 in developing male germ cells : RA-RhoGAP as a possible direct down-stream effector
No full textRap1 is a small GTPase that functions as a positional signal and organizer of cell architecture. Recently Rap1 is emerged to play a critical role during sperm differentiation since its inactivation in haploid cells leads to a premature release of spermatids from the supporting Sertoli cell resulting in male infertility. How Rap1 is activated in spermatogenic cells has not yet been determined. Our objective was to investigate on a possible cAMP-mediated activation of Rap1 employing a cAMP analogue selective to Epac, the Rap1 activator directly responsive to cAMP, for stimulating cultured testis germ cells. Here we provide biochemical, cellular and functional evidence that the Epac variant known as Epac2 is expressed as both a transcript and a protein and that it is able to promote Rap1 activation in the cultured cells. A time course immunofluorescence analysis carried out on stimulated cells revealed the translocation of endogenous Epac2, which is cytosolic, towards the site where Rap1 is located, i.e., the Golgi complex, thus documenting the effective Rap1-Epac2 protein interaction 'in vivo' leading to Rap1-GTP loading. A combination of biochemical and molecular techniques supported the immunofluorescence data. The search for the presence of a putative Rap1 downstream effector, described in differentiating somatic cells as a target of cAMP-Epac-activated Rap1, revealed the presence in spermatogenic cells of RA-RhoGAP, a Rap1-activated Rho GTPase-activating protein. Taken together, our results, obtained with endogenously expressed proteins, are consistent with a cAMP/Epac2/Rap1-mediated signaling that could exert its action, among others, through RA-RhoGAP to promote the progression of spermatogenesis
Severe acute multineuropathy in Churg-Strauss syndrome in a patient with a history of melanoma
No full textWe describe the clinicopathologic features of a 69-year-old mail affected with acute onset Churg-Strauss syndrome with major peripheral nerve involvement. At admision the patient presented a one-week history of distal upper-limb asymmetrical paresthesias. Asthma had been present since the age of 55 and treated with leukotriene receptor antagonists (LTAs, Montelukast) fora few years. Multiple pulmonary infiltrates had been diagnosed during follow-up for melanoma. During hospitalization lie showed rapidly progressive weakness worsening within a few hours; cerebrospinal fluid analysis, cervical MRI, head CT scan, nerve conduction Studies and peripheral nerve and skeletal muscle biopsies were performed. Blood analysis showed leukocytosis and marked eosinophilia; p-ANCA were positive. Sural nerve biopsy showed a marked loss of myelinated fibers, thrombosed vessels surrounded by mononuclear and eosinophilic cells, necrotizing and hyaline degeneration. Eosinophilic infiltrates were shown in MayGaunwald-Giemsa stained sections. The eosinophils mostly Occupied the Outer zone of the adventitia at the margin of the active lesion. Perivascular cellular infiltrates within the epineurium were immunoreactive for T-lyrnphocytes and macrophages. Strong HLA-DR immunostaining was present in the perineurium and membrane attack complex deposition was present in a few endoneurial capillaries. Muscle biopsy showed neurogenic changes and one Vessel surrounded by mononuclear cells. After a few days of corticosteroid therapy leukocytosis and eosinophilia normalized and the patient's clinical features stabilized
The novel mitochondrial tRNAAsn gene mutation m.5709T>C produces ophthalmoparesis and respiratory impairment
No full textAlthough mutations in mitochondrial tRNAs constitute the most common mtDNA defect, the presence of pathological variants in mitochondrial tRNA(Asn) is extremely rare. We were able to identify a novel mtDNA tRNA(Asn) gene pathogenic mutation associated with a myopathic phenotype and a previously unreported respiratory impairment. Our proband is an adult woman with ophthalmoparesis and respiratory impairment. Her muscle biopsy presented several cytochrome c oxidase-negative (COX-) fibres and signs of mitochondrial proliferation (ragged red fibres). Sequence analysis of the muscle-derived mtDNA revealed an m.5709T>C substitution, affecting mitochondrial tRNAAsn gene. Restriction-fragment length polymorphism analysis of the mutation in isolated muscle fibres showed that a threshold of at least 91.9% mutated mtDNA results in the COX deficiency phenotype. The new phenotype further increases the clinical spectrum of mitochondrial diseases caused by mutations in the tRNAAsn gene
Dr. Duane M. Jackson, Morehouse College, July 2011
No full textThis video is a conversation with Dr. Duane M. Jackson. Dr. Jackson talks about his paper, "Recall and the Serial Position Effect: The Role of Primacy and Recency on Accounting Students' Performance." Jackie Daniel, AUC Woodruff Library, is the interviewer
"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States" By M. Carey.
No full text"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States: containing bried sketches of the moral and political character of those states.
By M. Carey, member of the American philosophical, and of the American Antiquarian Society, and author of The Olive Branch, Cindiciae Hibernicae, essays on banking, on political economy, and on internal improvement.
To which are now added the English editor's comments on the subject; together with Important Advice to Emigrants, and Cautions Against Impositions Practiced in the Outports
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